In 1954, Fulton was elected to the Tennessee State Senate in place of his brother Lyle, who had died suddenly shortly after receiving the Democratic nomination for that post. Fulton was sworn in on January 3, 1955. However, he had not yet turned 30, the age required for senators under the Tennessee State Constitution. His election was challenged on this basis, and the Senate voted unanimously (28-0) to unseat Fulton,[1] whose post was then taken by Clifford Allen. Fulton ran for the position again in 1956, and this time was of age and seated. He was reelected in 1958, then left politics to begin a career in real estate.

In 1962 he entered the Democratic primary for the Nashville-based 5th Congressional District against incumbent Congressman Joseph Carlton Loser. In the August voting, Loser was the apparent victor. However, the election was contested by Fulton and a minor candidate, union activist Raymond Love. A subsequent series of articles on the front page of the Nashville Tennessean and a lawsuit followed. The allegations of fraud were serious enough that a judge ordered a new primary election. Love did not participate in this race, stating that his only desire had been one for an open, honest election and that the fraud alleged, while sufficient to have perhaps thwarted the election of Fulton, had not been of an extent sufficient to have prevented his election in any event. In the closely monitored rematch, Fulton defeated Loser rather handily, and breezed to victory in November.

Fulton was handily reelected in 1964, but in the next four cycles came closer than any Democrat before or since to losing a district that has been in Democratic hands since 1875. While his opponents were unwilling to state it publicly, much of the opposition to Fulton among some voters was his unabashed support for the Civil Rights Act of 1964, which most whiteSouthern Democrats actively opposed.

In 1966, 1968, and 1970, his Republican opponent was George Kelly, who owned a prominent flower shop in the Nashville suburb of Donelson. In 1968, Kelly almost defeated Fulton, losing by only four points—the closest any Republican has come, before or since, to winning the seat. It is very likely that Kelly would have won but for the presence of a candidate running under the banner of George Wallace's American Independent Party, who siphoned off enough conservative votes to keep Fulton in office. Wallace actually carried Nashville in that year's presidential election--the first time since the end of Reconstruction that the Democrats had failed to carry the city in a presidential election. Despite Kelly's repeated efforts to brand Fulton as an "ultra-liberal" in television spots, his campaign faltered in 1970, and he decided not to run for Congress again. (He later achieved regional fame around Nashville as the man who paid young people $10 for memorizing the Ten Commandments.) In 1972, Fulton faced a fairly well funded challenge from attorney Alf Adams, who tried to tie Fulton to Democratic presidential nominee George McGovern. However, Adams was badly defeated, winning only 38% of the vote to 62% for Fulton. This was a considerable embarrassment to the Republicans, since Richard Nixon carried Nashville by a substantial margin—the first Republican to do so since Reconstruction—with the support of many local Democrats, including Mayor Beverly Briley. The Republicans have only put up nominal challengers in the 5th since then.

Fulton was very well known in Nashville and the immediate area, but quite obscure outside of it. He was a staunch supporter of music interests in his votes, taking especial interest in areas such as copyrightlaw. This may have in part been because Fulton, like many Nashvillians, was an amateursongwriter himself, at one point recording a song in 1968 about a paperboy somewhat like the one that he had been in his youth ("Poor Little Paperboy" b/w "A Dozen Yellow Roses" - RCA 47-9412). This interest landed him a slot as a contestant on the To Tell the Truthgame show as the song-writing Congressman. (The show was not regarded as particularly dramatic in the Nashville area, however.)

In 1975, Briley, the only mayor Nashville had ever had since its consolidation with Davidson County, was barred from a fourth term by the Metro Charter. A secretive group of Nashville business leaders known as "Watauga" (after the area in East Tennessee from which the original white settlers of Nashville had migrated), was not impressed with the prospective successors that they saw among local political leaders. They approached Fulton and promised him that he would almost certainly win if he ran. This proved prophetic, as Fulton won the race that year with almost a two-thirds majority. His only major opponent, Criminal Court Clerk Earl Hawkins, received about 25%. (In contrast, the third-place finisher, plumbing-supply store operator Ralph Cohen, received only about 6%.) He was succeeded in Washington by Clifford Allen.

Fulton's second term for the most part went more smoothly, and his 1983 reelection came much more easily. In 1986 Fulton again ran for governor, again finishing third in the Democratic primary, behind state Speaker of the HouseNed McWherter, and another Public Service Commissioner, Jane Eskind. This time, some of Fulton's detractors accused him of particularly heavy spending on public works projects in predominantly black areas of Nashville, and implied that this was a repeat of the pattern of eight years prior, with mysteriously little work having taken place in the area on these projects in the interim.

Fulton was the driving force behind the construction of the Nashville Convention Center in downtown Nashville during the mid-1980s. Almost immediately after its 1987 opening, it was considered antiquated: too small, somewhat inaccessible, and unable to expand. Another larger, privately owned convention center was already open at the Opryland Hotel just a few miles away during that time, causing the downtown convention center to be overshadowed almost from its beginning. Even now, the NCC primarily books small functions and local events, while the Opryland convention center draws more corporate events and conventions from out of town. Therefore, the Nashville Convention Center has always carried the nickname "Fulton's Folly" in some circles.

Fulton was barred by the Metro Charter from running for a fourth consecutive term, and was succeeded by another member of Congress, Bill Boner. He was not far removed from public service, as his wife Sandra served in McWherter's Cabinet as Commissioner of Tourism. Fulton devoted his time to his family's real estate business and his governmental-relations consulting firm, and occasionally appeared in Nashville media as an expert political commentator.

However, when mayor Phil Bredesen did not run for reelection as mayor in 1999 (it is still unclear whether a term limits provision amended into the Nashville Metro Charter after Fulton's time as mayor limiting city council members to two consecutive four-year terms applies to mayors, superseding the former three-term limit; Bredesen chose not to contest this point), Fulton was again encouraged to run. From the outset of the 1999 race, it was apparent that there were actually three serious candidates: Fulton; Vice Mayor Jay West, son of 1950s Nashville mayor Ben West and brother of popular state representative Ben West, Jr.; and former State House Majority Leader and Vanderbilt University employee Bill Purcell. Purcell received almost a majority of the votes, narrowly missing outright victory; Fulton finished a very distant second, just ahead of West. Since the Metro Charter requires mayors and city councilmen to win a majority, ordinarily a runoff would have occurred. However, Fulton announced shortly after the election that he felt that Purcell had won sufficiently and that he would not be contesting the runoff. By law, the runoff had to occur nonetheless; it was also necessary for some city council races, but Fulton's announcement meant that there was very little remaining interest, and hence a very low turnout, for the runoff when it did occur three weeks later. Purcell naturally won easily, which was apparently the outcome foreseen by Fulton and his supporters whether they had continued to contest the race or not.

Fulton returned to his real estate and consulting interests, which he still pursues as of 2005[update].